Bsi bs en 61747 6 2 2011 (2012)

• A flat Lambertian luminance source parallel to the DUT-surface produces an illumination of the measuring spot that drops with cos4θ θ is the angle of inclination of the direction of Fi

BSI Standards Publication

Liquid crystal display devices

Part 6-2: Measuring methods for liquid crystal display modules — Reflective type

© BSI 2011 ISBN 978 0 580 58325 4 ICS 31.120

Compliance with a British Standard cannot confer immunity from legal obligations.

This British Standard was published under the authority of the Standards Policy and Strategy Committee on 31 August 2011

Amendments issued since publication

This British Standard is the UK implementation of EN 61747-6-2:2011 It is idenitical to IEC 61747-6-2:2011

The UK participation in its preparation was entrusted to Technical Committee EPL/47, Semiconductors

A list of organizations represented on this committee can be obtained on request to its secretary

This publication does not purport to include all the necessary provisions of a contract Users are responsible for its correct application

© BSI 2011 ISBN 978 0 580 58325 4 ICS 31.120

Compliance with a British Standard cannot confer immunity from legal obligations.

This British Standard was published under the authority of the Standards Policy and Strategy Committee on 31 August 2011

Amendments issued since publication

This British Standard is the UK implementation of EN 61747-6-2:2011

It is identical to IEC 61747-6-2:2011, incorporating corrigendum January 2012

The start and finish of text introduced or altered by corrigendum

is indicated in the text by tags Text altered by IEC corrigendum January 2012 is indicated in the text by 

© The British Standards Institution 2013

Published by BSI Standards Limited 2013ISBN 978 0 580 78491 0

Amendments/corrigenda issued since publication

31 May 2013 Implementation of IEC corrigendum

January 2012

NORME EUROPÉENNE

CENELEC European Committee for Electrotechnical Standardization Comité Européen de Normalisation Electrotechnique Europäisches Komitee für Elektrotechnische Normung

Management Centre: Avenue Marnix 17, B - 1000 Brussels

© 2011 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members

Dispositifs d'affichage à cristaux liquides -

Partie 6-2: Méthodes de mesure pour les

modules d'affichage à cristaux liquides -

Type réflexible

(CEI 61747-6-2:2011)

Flüssigkristall-Anzeige-Bauelemente - Teil 6-2: Messverfahren für Flüssigkristall- Anzeigemodule -

Reflektive Ausführung (IEC 61747-6-2:2011)

This European Standard was approved by CENELEC on 2011-07-15 CENELEC members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration

Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the Central Secretariat or to any CENELEC member

This European Standard exists in three official versions (English, French, German) A version in any other language made by translation under the responsibility of a CENELEC member into its own language and notified

to the Central Secretariat has the same status as the official versions

CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Croatia, Cyprus, the Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and the United Kingdom

The following dates were fixed:

– latest date by which the EN has to be implemented

at national level by publication of an identical

– latest date by which the national standards conflicting

Annex ZA has been added by CENELEC

Endorsement notice

The text of the International Standard IEC 61747-6-2:2011 was approved by CENELEC as a European Standard without any modification

In the official version, for Bibliography, the following notes have to be added for the standards indicated:

[19] IEC 61747-6 NOTE Harmonized as EN 61747-6

[20] ISO 9241-7 NOTE Harmonized as EN ISO 9241-7

[21] ISO 13406-2 NOTE Harmonized as EN ISO 13406-2

[23] IEC 61747-1 NOTE Harmonized as EN 61747-1

[24] IEC 61747-5 NOTE Harmonized as EN 61747-5

The following referenced documents are indispensable for the application of this document For dated

references, only the edition cited applies For undated references, the latest edition of the referenced

document (including any amendments) applies

CIE 38 - Radiometric and photometric characteristics of

CONTENTS

FOREWORD 5

INTRODUCTION 7

1 Scope 8

2 Normative references 8

3 Illumination and illumination geometry 9

3.1 General comments and remarks on the measurement of reflective LCDs 9

3.2 Viewing-direction coordinate system 9

3.3 Basic illumination geometries 10

3.4 Realization of illumination geometries 10

3.4.1 General 10

3.4.2 Directional illumination 11

3.4.3 Ring-light illumination 11

3.4.4 Conical illumination 12

3.4.5 Hemispherical illumination 12

4 Standard measurement equipment and set-up 13

4.1 Light measuring devices (LMD) 13

4.2 Positioning and alignment 13

4.3 Standard measurement arrangements 13

4.3.1 General 13

4.3.2 Directional illumination 14

4.3.3 Ring-light illumination 15

4.3.4 Conical illumination 15

4.3.5 Hemispherical illumination 16

4.3.6 Other illumination conditions 17

4.4 Standard specification of measurement conditions 17

4.4.1 Illumination conditions 17

4.4.2 LMD conditions 19

4.4.3 Unwanted effects of receiver inclination 20

4.4.4 Control and suppression of front-surface reflections 20

4.5 Working standards and references 21

4.5.1 Diffuse reflectance standard 21

4.5.2 Specular reflectance standard 21

4.6 Standard locations of measurement field 22

4.6.1 Matrix displays 22

4.6.2 Segment displays 22

4.7 Standard DUT operating conditions 23

4.7.1 General 23

4.7.2 Standard ambient conditions 23

4.8 Standard measuring process 23

5 Standard measurements and evaluations 24

5.1 Reflectance – Photometric 24

5.1.1 Purpose 24

5.1.2 Measuring equipment 24

5.1.3 Measuring method 24

5.1.4 Definitions and evaluations 25

5.2 Contrast ratio 26

CONTENTS

FOREWORD 5

INTRODUCTION 7

1 Scope 8

2 Normative references 8

3 Illumination and illumination geometry 9

3.1 General comments and remarks on the measurement of reflective LCDs 9

3.2 Viewing-direction coordinate system 9

3.3 Basic illumination geometries 10

3.4 Realization of illumination geometries 10

3.4.1 General 10

3.4.2 Directional illumination 11

3.4.3 Ring-light illumination 11

3.4.4 Conical illumination 12

3.4.5 Hemispherical illumination 12

4 Standard measurement equipment and set-up 13

4.1 Light measuring devices (LMD) 13

4.2 Positioning and alignment 13

4.3 Standard measurement arrangements 13

4.3.1 General 13

4.3.2 Directional illumination 14

4.3.3 Ring-light illumination 15

4.3.4 Conical illumination 15

4.3.5 Hemispherical illumination 16

4.3.6 Other illumination conditions 17

4.4 Standard specification of measurement conditions 17

4.4.1 Illumination conditions 17

4.4.2 LMD conditions 19

4.4.3 Unwanted effects of receiver inclination 20

4.4.4 Control and suppression of front-surface reflections 20

4.5 Working standards and references 21

4.5.1 Diffuse reflectance standard 21

4.5.2 Specular reflectance standard 21

4.6 Standard locations of measurement field 22

4.6.1 Matrix displays 22

4.6.2 Segment displays 22

4.7 Standard DUT operating conditions 23

4.7.1 General 23

4.7.2 Standard ambient conditions 23

4.8 Standard measuring process 23

5 Standard measurements and evaluations 24

5.1 Reflectance – Photometric 24

5.1.1 Purpose 24

5.1.2 Measuring equipment 24

5.1.3 Measuring method 24

5.1.4 Definitions and evaluations 25

5.2 Contrast ratio 26

5.2.1 Purpose 26

5.2.2 Measuring equipment 26

5.2.3 Measurement method 26

5.2.4 Definitions and evaluations 27

5.3 Peak viewing direction / viewing angle range 27

5.3.1 Purpose / definition 27

5.3.2 Measuring equipment 27

5.3.3 Viewing angle 27

5.3.4 Viewing angle range without gray-level inversion 28

5.3.5 Specular reflectance from the active area surface 29

5.4 Chromaticity 31

5.4.1 Purpose 31

5.4.2 Measuring equipment 31

5.4.3 Measuring method 31

5.4.4 Definitions and evaluations 31

5.4.5 Specified conditions 32

5.5 Electro-optical transfer function – Photometric 33

5.5.1 Purpose 33

5.5.2 Set-up 33

5.5.3 Procedure 33

5.5.4 Evaluation and representation 33

5.6 Electro-optical transfer function – Colorimetric 34

5.6.1 Purpose 34

5.6.2 Set-up 34

5.6.3 Procedure 34

5.6.4 Evaluation and representation 35

5.7 Lateral variations (photometric, colorimetric) 35

5.7.1 Purpose 35

5.7.2 Measuring equipment 35

5.7.3 Uniformity of reflectance 36

5.7.4 Uniformity of white 36

5.7.5 Uniformity of chromaticity 37

5.7.6 Uniformity of primary colours 37

5.7.7 Cross-talk 38

5.7.8 Specified conditions 40

5.8 Temporal variations 40

5.8.1 Response time 40

5.8.2 Flicker / frame response (multiplexed displays) 43

5.8.3 Specified conditions 44

5.9 Electrical characteristics 45

5.9.1 Purpose 45

5.9.2 Measuring instruments 45

5.9.3 Measuring method 45

5.9.4 Definitions and evaluations 45

5.9.5 Specified conditions 46

Annex A (informative) Standard measuring conditions 47

Bibliography 51

Figure 1 – Representation of the viewing-direction (equivalent to the direction of

measurement) by the angle of inclination, θ and the angle of rotation (azimuth angle),

φ in a polar coordinate system 9

Figure 2 – Directional illumination with a flat source disk 10

Figure 3 – Realization alternatives for directional illumination 11

Figure 4 – Examples of ring-light illumination 12

Figure 5 – Examples of conical illumination with a spherical dome (left) and an integrating sphere with large aperture (right) 12

Figure 6 – Examples of hemispherical illumination 13

Figure 7 – Side-view of the measuring set-up using directional illumination 14

Figure 8 – Side-view of the ring-light illumination measuring set-up 15

Figure 9 – Side-view of the conical illumination measuring set-up 16

Figure 10 – Side-view of the hemispherical illumination measuring set-up 17

Figure 11 – Hemispherical illumination with gloss-trap (GT) opposite to receiver inclination 18

Figure 12 – Normalized illuminance at the location of the measuring spot 18

Figure 13 – Lines of equal chromaticity differences ∆u' (left), ∆v' (right) 19

Figure 14 – Shape of measuring spot on DUT for two angles of receiver inclination 20

Figure 15 – Reflections from the first surface of a transparent medium (glass substrate, polarizer, etc.) superimposed to the reflection component that is modulated by the display device 21

Figure 16 – Standard measurement positions are at the centres of all rectangles p0-p24 Height and width of each rectangle is 20 % of display height and width respectively 22

Figure 17 – Example of standard set-up for specular reflection measurements 30

Figure 18 – Example of equipment for measurement of temporal variations 41

Figure 19 – Relationship between driving signal and optical response times 42

Figure 20 – Frequency characteristics of the integrator (response of human visual system) 44

Figure 21 – Example of power spectrum 44

Figure 22 – Checker-flag pattern for current and power consumption measurements 45

Figure 23 – Example of measuring block diagram for current and power consumption of a liquid crystal display device 46

Figure A.1 – Coordinate system for measurement of the BRDF, index "i" for incident light, index "r" for reflected light Directions are described by two angles, θ and φ (inclination and azimuth) in a polar coordinate system as shown 48

Figure A.2 – Terminology for LMDs 49

Figure 1 – Representation of the viewing-direction (equivalent to the direction of

measurement) by the angle of inclination, θ and the angle of rotation (azimuth angle),

φ in a polar coordinate system 9

Figure 2 – Directional illumination with a flat source disk 10

Figure 3 – Realization alternatives for directional illumination 11

Figure 4 – Examples of ring-light illumination 12

Figure 5 – Examples of conical illumination with a spherical dome (left) and an integrating sphere with large aperture (right) 12

Figure 6 – Examples of hemispherical illumination 13

Figure 7 – Side-view of the measuring set-up using directional illumination 14

Figure 8 – Side-view of the ring-light illumination measuring set-up 15

Figure 9 – Side-view of the conical illumination measuring set-up 16

Figure 10 – Side-view of the hemispherical illumination measuring set-up 17

Figure 11 – Hemispherical illumination with gloss-trap (GT) opposite to receiver inclination 18

Figure 12 – Normalized illuminance at the location of the measuring spot 18

Figure 13 – Lines of equal chromaticity differences ∆u' (left), ∆v' (right) 19

Figure 14 – Shape of measuring spot on DUT for two angles of receiver inclination 20

Figure 15 – Reflections from the first surface of a transparent medium (glass substrate, polarizer, etc.) superimposed to the reflection component that is modulated by the display device 21

Figure 16 – Standard measurement positions are at the centres of all rectangles p0-p24 Height and width of each rectangle is 20 % of display height and width respectively 22

Figure 17 – Example of standard set-up for specular reflection measurements 30

Figure 18 – Example of equipment for measurement of temporal variations 41

Figure 19 – Relationship between driving signal and optical response times 42

Figure 20 – Frequency characteristics of the integrator (response of human visual system) 44

Figure 21 – Example of power spectrum 44

Figure 22 – Checker-flag pattern for current and power consumption measurements 45

Figure 23 – Example of measuring block diagram for current and power consumption of a liquid crystal display device 46

Figure A.1 – Coordinate system for measurement of the BRDF, index "i" for incident light, index "r" for reflected light Directions are described by two angles, θ and φ (inclination and azimuth) in a polar coordinate system as shown 48

Figure A.2 – Terminology for LMDs 49

INTERNATIONAL ELECTROTECHNICAL COMMISSION

_

LIQUID CRYSTAL DISPLAY DEVICES – Part 6-2: Measuring methods for liquid crystal display modules –

Reflective type

FOREWORD 1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising all national electrotechnical committees (IEC National Committees) The object of IEC is to promote international co-operation on all questions concerning standardization in the electrical and electronic fields To this end and in addition to other activities, IEC publishes International Standards, Technical Specifications, Technical Reports, Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC Publication(s)”) Their preparation is entrusted to technical committees; any IEC National Committee interested

in the subject dealt with may participate in this preparatory work International, governmental and non-governmental organizations liaising with the IEC also participate in this preparation IEC collaborates closely with the International Organization for Standardization (ISO) in accordance with conditions determined by agreement between the two organizations

2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international consensus of opinion on the relevant subjects since each technical committee has representation from all interested IEC National Committees

3) IEC Publications have the form of recommendations for international use and are accepted by IEC National Committees in that sense While all reasonable efforts are made to ensure that the technical content of IEC Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any misinterpretation by any end user

4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications transparently to the maximum extent possible in their national and regional publications Any divergence between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in the latter

5) IEC itself does not provide any attestation of conformity Independent certification bodies provide conformity assessment services and, in some areas, access to IEC marks of conformity IEC is not responsible for any services carried out by independent certification bodies

6) All users should ensure that they have the latest edition of this publication

7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and members of its technical committees and IEC National Committees for any personal injury, property damage or other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC Publications

8) Attention is drawn to the Normative references cited in this publication Use of the referenced publications is indispensable for the correct application of this publication

9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of patent rights IEC shall not be held responsible for identifying any or all such patent rights

International Standard IEC 61747-6-2 has been prepared by IEC technical committee 110: Flat panel display devices

This standard should be read together with the generic specification to which it refers

The text of this standard is based on the following documents:

FDIS Report on voting 110/281/FDIS 110/299/RVD

Full information on the voting for the approval on this standard can be found in the report on voting indicated in the above table

This publication has been drafted in accordance with the ISO/IEC Directives, Part 2

A list of all the parts in the IEC 61747 series, under the general title Liquid crystal display

devices, can be found on the IEC website

Future standards in this series will carry the new general title as cited above Titles of existing standards in this series will be updated at the time of the next edition

The committee has decided that the contents of this publication will remain unchanged until the stability date indicated on the IEC web site under "http://webstore.iec.ch" in the data related to the specific publication At this date, the publication will be

A list of all the parts in the IEC 61747 series, under the general title Liquid crystal display

devices, can be found on the IEC website

Future standards in this series will carry the new general title as cited above Titles of existing

standards in this series will be updated at the time of the next edition

The committee has decided that the contents of this publication will remain unchanged until

the stability date indicated on the IEC web site under "http://webstore.iec.ch" in the data

related to the specific publication At this date, the publication will be

• reconfirmed,

• withdrawn,

• replaced by a revised edition, or

• amended

IMPORTANT – The 'colour inside' logo on the cover page of this publication indicates that it

contains colours which are considered to be useful for the correct understanding of its

contents Users should therefore print this document using a colour printer

INTRODUCTION

In order to achieve a useful and uniform description of the performance of these devices, specifications for commonly accepted relevant parameters are put forward These fall into the following categories:

a) general type specification (e.g pixel resolution, diagonal, pixel layout);

b) optical specification (e.g contrast ratio, response time, viewing direction, crosstalk, etc.);

c) electrical specification (e.g power consumption, EMC);

d) mechanical specification (e.g module geometry, weight);

e) specification of passed environmental endurance test;

f) specification of reliability and hazard / safety

In most of the above cases, the specification is self-explanatory For some specification points however, notably in the area of optical and electrical performance, the specified value may depend on the measuring method

It is assumed that all measurements are performed by personnel skilled in the general art of radiometric and electrical measurements as the purpose of this standard is not to give a detailed account of good practice in electrical and optical experimental physics Furthermore,

it must be assured that all equipment is suitably calibrated as is known to people skilled in the art and records of the calibration data and traceability are kept

LIQUID CRYSTAL DISPLAY DEVICES – Part 6-2: Measuring methods for liquid crystal display modules –

Reflective type

1 Scope

This part of IEC 61747 gives details of the quality assessment procedures, the inspection requirements, screening sequences, sampling requirements, and test and measurement procedures required for the assessment of liquid crystal display modules

This standard is restricted to reflective liquid crystal display-modules using either segment, passive or active matrix and a-chromatic or colour type LCDs (see Note) Furthermore, the reflective modes of transflective LCD modules with backlights OFF and reflective LCD modules of front light type without its front-light-unit, are comprised in this standard A reflective LCD module with combination of a touch-key-panel or a front-light-unit is out of the scope of this standard, because its measurements are frequently inaccurate Its touch-key-panel or front-light-unit should be removed before it can be included in this scope

NOTE Several points of view with respect to the preferred terminology on "monochrome", "achromatic",

"chromatic", "colour", "full-colour", etc can be encountered in the field amongst spectroscopists, (general-) physicists, colour-perception scientists, physical engineers and electrical engineers In general, all LCDs demonstrate some sort of chromaticity (e.g as function of viewing angle, ambient temperature or externally addressable means) Pending detailed official description of the subject, the pre-fix pertaining to the "chromaticity"

of the display will be used so as to describe the colour capability of the display that is externally (and electrically) addressable by the user This leads us to the following definitions (see also [19])

a) a monochrome display has NO user-addressable chromaticity ("colours") It may or may not be "black and white" or a-chromatic;

b) a colour display has at least two user-addressable chromaticities ("colours") A 64-colour display has 64 addressable colours (often made using 2 bits per primary for 3 primaries), etc A full-colour display has at least 6 bits per primary (≥ 260 thousand colours)

The purpose of this standard is to indicate and list the procedure-dependent parameters and

to prescribe the specific methods and conditions that are to be used for their uniform numerical determination

2 Normative references

The following referenced documents are indispensable for the application of this document For dated references, only the edition cited applies For undated references, the latest edition

of the referenced document (including any amendments) applies

ISO 11664-2:2007, Colorimetry – Part 2: CIE standard illuminants

CIE 15.2, CIE Recommendations on Colorimetry

CIE 17.4, International Lighting Vocabulary

CIE 38, Radiometric and photometric characteristics of materials and their measurement CIE 1931, CIE XYZ colour space

CIE 1976, CIE LAB colour space

LIQUID CRYSTAL DISPLAY DEVICES – Part 6-2: Measuring methods for liquid crystal display modules –

Reflective type

1 Scope

This part of IEC 61747 gives details of the quality assessment procedures, the inspection

requirements, screening sequences, sampling requirements, and test and measurement

procedures required for the assessment of liquid crystal display modules

This standard is restricted to reflective liquid crystal display-modules using either segment,

passive or active matrix and a-chromatic or colour type LCDs (see Note) Furthermore, the

reflective modes of transflective LCD modules with backlights OFF and reflective LCD

modules of front light type without its front-light-unit, are comprised in this standard A

reflective LCD module with combination of a touch-key-panel or a front-light-unit is out of the

scope of this standard, because its measurements are frequently inaccurate Its

touch-key-panel or front-light-unit should be removed before it can be included in this scope

NOTE Several points of view with respect to the preferred terminology on "monochrome", "achromatic",

"chromatic", "colour", "full-colour", etc can be encountered in the field amongst spectroscopists, (general-)

physicists, colour-perception scientists, physical engineers and electrical engineers In general, all LCDs

demonstrate some sort of chromaticity (e.g as function of viewing angle, ambient temperature or externally

addressable means) Pending detailed official description of the subject, the pre-fix pertaining to the "chromaticity"

of the display will be used so as to describe the colour capability of the display that is externally (and electrically)

addressable by the user This leads us to the following definitions (see also [19])

a) a monochrome display has NO user-addressable chromaticity ("colours") It may or may not be "black and

white" or a-chromatic;

b) a colour display has at least two user-addressable chromaticities ("colours") A 64-colour display has 64

addressable colours (often made using 2 bits per primary for 3 primaries), etc A full-colour display has at

least 6 bits per primary (≥ 260 thousand colours)

The purpose of this standard is to indicate and list the procedure-dependent parameters and

to prescribe the specific methods and conditions that are to be used for their uniform

numerical determination

2 Normative references

The following referenced documents are indispensable for the application of this document

For dated references, only the edition cited applies For undated references, the latest edition

of the referenced document (including any amendments) applies

ISO 11664-2:2007, Colorimetry – Part 2: CIE standard illuminants

CIE 15.2, CIE Recommendations on Colorimetry

CIE 17.4, International Lighting Vocabulary

CIE 38, Radiometric and photometric characteristics of materials and their measurement

CIE 1931, CIE XYZ colour space

CIE 1976, CIE LAB colour space

3 Illumination and illumination geometry

3.1 General comments and remarks on the measurement of reflective LCDs

Reflective LCDs make use of the ambient illumination to display visual information; often, they

do not posses their own integrated source of illumination It is difficult to achieve the required significance and reproducibility of the results of measurements because of the close coupling between the apparatus providing the illumination, the LMD (light measuring device) and the device under test (DUT) This dependence of results on the instrumentation implies that e.g the contrast of reflective LCDs is not an intrinsic property of the device itself, but the contrast can only be evaluated under specific and well defined conditions for illumination and detection [3]1, [4], [5], [6], [7], [8] [.]

This part describes a selection of different geometries suitable for measuring and characterizing reflective LCDs as a function of the direction of observation (i.e viewing-direction = direction of measurement), as examples The range of geometries for illumination

of the DUT and detection of the light reflected from the DUT shall not be limited to the examples presented here A set of parameters provides detailed specification of the conditions that are used for measurement of the electro-optical characteristics as listed below

3.2 Viewing-direction coordinate system

The viewing-direction is the direction under which the observer looks at the spot of interest on the display During the measurement the light-measuring device replaces the observer, looking from the same direction at a specified spot (i.e measuring spot, measurement field)

on the DUT The viewing-direction is conveniently defined by two angles: the angle of inclination θ (related to the surface normal of the DUT) and the angle of rotation φ (also called azimuth angle) as illustrated in Figure 1 The azimuth angle is related with the directions on a watch-dial as follows: refer to φ = 0 ° as the 3 o'clock direction ("right"), to φ = 90 ° as the

12 o'clock direction ("top"), φ = 180 ° as the 9 o'clock direction ("left") and to φ = 270 ° as the

6 o'clock direction ("bottom")

Figure 1 – Representation of the viewing-direction (equivalent to the direction of measurement)

by the angle of inclination, θ and the angle of rotation (azimuth angle), φ in a polar coordinate system

—————————

1 Figures in square brackets refer to the bibliography

IEC 951/11

3.3 Basic illumination geometries

Typical illumination geometries are (according to CIE 38):

• directional illumination

An illumination source where the incident rays are approximately parallel (max deviation from optical axis < 5 °) is directed at the DUT, the direction of illumination is specified by θ and φ The intensity across the cross-section of the beam shall be constant within 5 % Any source of light sufficiently distant from the DUT provides a directional illumination (e.g sun, moon) Figure 2 provides an example of directional illumination with a flat source disk (Lambertian

emission) of radius r s , distance to measuring spot d and measuring spot radius r ms

The maximum deviation from the optical axis is depending on the diameter of both source and measuring spot The maximum angle of deviation from the optical axis is given by the following Equation (1)

• conical illumination

Illumination is provided out of an extended solid angle ΩSC with the apex of this solid angle fixed to the centre of the measuring spot on the DUT The variation of illuminance with direction inside this solid angle shall be specified The recommended method for measuring this variation is given in Annex A The cone of illumination itself is specified by the direction of the axis of the cone and the maximum inclination with respect to the axis (i.e cone-angle)

Mixtures and modifications of the three basic illumination geometries are possible as long as the conditions are sufficiently specified

3.3 Basic illumination geometries

Typical illumination geometries are (according to CIE 38):

• directional illumination

An illumination source where the incident rays are approximately parallel (max deviation from

optical axis < 5 °) is directed at the DUT, the direction of illumination is specified by θ and φ

The intensity across the cross-section of the beam shall be constant within 5 % Any source of

light sufficiently distant from the DUT provides a directional illumination (e.g sun, moon)

Figure 2 provides an example of directional illumination with a flat source disk (Lambertian

emission) of radius r s , distance to measuring spot d and measuring spot radius r ms

The maximum deviation from the optical axis is depending on the diameter of both source and

measuring spot The maximum angle of deviation from the optical axis is given by the

following Equation (1)

• conical illumination

Illumination is provided out of an extended solid angle ΩSC with the apex of this solid angle

fixed to the centre of the measuring spot on the DUT The variation of illuminance with

direction inside this solid angle shall be specified The recommended method for measuring

this variation is given in Annex A The cone of illumination itself is specified by the direction of

the axis of the cone and the maximum inclination with respect to the axis (i.e cone-angle)

• hemispherical illumination

Illumination is provided out of a wide solid angle ΩSH with the apex of this solid angle fixed to

the centre of the measuring spot on the DUT In the true hemispherical case the solid angle

ΩSH extends to an angle of inclination of 90 ° For the purpose of this standard, the term

hemispherical illumination shall be applicable when illumination is provided such that the

illuminance does not drop below 50 % of the maximum value at an angle of inclination of 60 °

The variation of luminous intensity with direction inside the solid angle ΩSH shall be specified

The recommended method for measuring this variation is given in Annex A

Mixtures and modifications of the three basic illumination geometries are possible as long as

the conditions are sufficiently specified

The three basic types of illumination can be realized in different ways as illustrated in this

clause Implementation results in the following four examples for geometries of illumination

IEC 952/11

3.4.2 Directional illumination

Directional illumination can be realized with three different types of sources when the source dimensions are kept small enough compared to the distance between source and the measuring field on the sample The following geometries are depicted in Figure 3:

• flat Lambertian source, e.g the exit port of an integrating sphere (top),

• spherical isotropic source (e.g incandescent bulb inside a diffusing glass-sphere) (middle),

• projection system with lenses or mirrors (bottom)

A ring-light illumination can be realized by application of :

• a ring-shaped fluorescent lamp (Figure 4a),

• fiber-optical ring-light,

• integrating sphere with a ring-shaped aperture (annulus) (Figure 4b),

• others

IEC 953/11

DUT

d

DUT

Figure 4a – Ring-shaped fluorescent lamp Figure 4b – Integrating sphere with annulus

NOTE Ring-light illumination is not intended to provide a diffuse illumination It provides a directed illumination with rotatory symmetry around the normal of the display in the measurement spot

Figure 4 – Examples of ring-light illumination 3.4.4 Conical illumination

Conical illumination can be realized with three different geometries:

• The exit port of an integrating sphere at some distance to the measuring spot produces a conical illumination with constant intensity from all directions of light incidence (Figure 5b)

• A hemispherical dome (reflective or transmissive section of a sphere) produces conical illumination (up to angles of inclination of e.g 80 °) usually with variations of the illuminance versus direction of light incidence (Figure 5a)

• A flat Lambertian luminance source parallel to the DUT-surface produces an illumination

of the measuring spot that drops with cos4θ (θ is the angle of inclination of the direction of light incidence)

DUT

d

DUT

Figure 5a – Spherical dome Figure 5b – Integrating sphere with large aperture

Figure 5 – Examples of conical illumination with a spherical dome (Figure 5a)

and an integrating sphere with large aperture (Figure 5b) 3.4.5 Hemispherical illumination

Good approximation of ideal hemispherical illumination (i.e constant illuminance from all directions up to 90 °) can only be provided by integrating spheres with a small exit port diameter compared to the diameter of the sphere The exit port must be directly adjacent to

IEC 954/11

IEC 955/11

DUT

d

DUT

Figure 4a – Ring-shaped fluorescent lamp Figure 4b – Integrating sphere with annulus

NOTE Ring-light illumination is not intended to provide a diffuse illumination It provides a directed illumination

with rotatory symmetry around the normal of the display in the measurement spot

Figure 4 – Examples of ring-light illumination 3.4.4 Conical illumination

Conical illumination can be realized with three different geometries:

• The exit port of an integrating sphere at some distance to the measuring spot produces a

conical illumination with constant intensity from all directions of light incidence (Figure 5b)

• A hemispherical dome (reflective or transmissive section of a sphere) produces conical

illumination (up to angles of inclination of e.g 80 °) usually with variations of the

illuminance versus direction of light incidence (Figure 5a)

• A flat Lambertian luminance source parallel to the DUT-surface produces an illumination

of the measuring spot that drops with cos4θ (θ is the angle of inclination of the direction of

Figure 5a – Spherical dome Figure 5b – Integrating sphere with large aperture

Figure 5 – Examples of conical illumination with a spherical dome (Figure 5a)

and an integrating sphere with large aperture (Figure 5b) 3.4.5 Hemispherical illumination

Good approximation of ideal hemispherical illumination (i.e constant illuminance from all

directions up to 90 °) can only be provided by integrating spheres with a small exit port

diameter compared to the diameter of the sphere The exit port must be directly adjacent to

Other approximations of hemispherical illumination may be realized by:

• diffusing hemispheres with diffuse reflective coatings (Figure 6b),

• transmissive diffusing spheres and domes

DUT

Figure 6a – Integrating sphere Figure 6b – Diffuse hemisphere

Figure 6 – Examples of hemispherical illumination

4 Standard measurement equipment and set-up

4.1 Light measuring devices (LMD)

The light measuring devices used for evaluation of the reflectance of reflective LCDs shall be checked for the following criteria and specified accordingly:

• sensitivity of the measured quantity to polarization of light,

• errors caused by veiling glare and lens flare (i.e stray-light in optical system),

• timing of data-acquisition, low-pass filtering and aliasing-effects,

• linearity of detection and data-conversion

4.2 Positioning and alignment

The LMD has to be positioned with respect to the measurement field on the DUT in order to adjust the direction of measurement (viewing-direction) and to adjust the distance from the centre of the measuring spot to assure an angular aperture of smaller than 5 ° Such adjustment can be realized with a mechanical system (often motorized) and alternatively with

an appropriate optical system (conoscopic optics) as described in e.g [9]

4.3 Standard measurement arrangements 4.3.1 General

The following standard measuring geometries are introduced:

a) directional illumination, b) ring-light illumination, c) conical illumination, d) hemispherical illumination

IEC 958/11

IEC 959/11

These geometries are frequently used, and extensive model calculations have been published concerning the reproducibility and repeatability of measurements done using these geometries [15]

4.3.2 Directional illumination

This is a light-source with a small diameter (compared to the distance to the measurement field) aligned to form an angle θS with respect to the surface-normal of the DUT This light source illuminates the DUT to form a directional illumination for the measurement field The LMD is in the plane of light incidence, aligned at an angle θR with respect to the surface normal of the DUT The measurement field on the DUT is defined by the area element that is imaged on the detector of the LMD

DUT

LMD Light

source

φ

θ

Figure 7a – Directional illumination – Side view Figure 7b – Directional illumination – Top view

Figure 7 – Side-view of the measuring set-up using directional illumination

The light-source as well as the LMD in this set-up can be adjusted to a range of angles of inclinations, but the LMD shall remain in the plane of light-incidence (i.e φS = φR + 180 °) Alignment accuracy to within 0,2 ° is required to achieve good reproducibility [15], [17]

This configuration is shown in Figure 7a, with its representation in a polar coordinate system (Figure 7b) for, in this example, an angle of LMD-inclination, θR = 30 ° and angle of source inclination, θS = 40 °

NOTE Standard conditions of θS = 0 ° and θR = 30 ° are recommended Alignment accuracy to within ± 0,4 ° is recommended to assure measurement error within ± 5 % [16]

IEC 960/11

IEC 961/11

These geometries are frequently used, and extensive model calculations have been published

concerning the reproducibility and repeatability of measurements done using these

geometries [15]

4.3.2 Directional illumination

This is a light-source with a small diameter (compared to the distance to the measurement

field) aligned to form an angle θS with respect to the surface-normal of the DUT This light

source illuminates the DUT to form a directional illumination for the measurement field The

LMD is in the plane of light incidence, aligned at an angle θR with respect to the surface

normal of the DUT The measurement field on the DUT is defined by the area element that is

imaged on the detector of the LMD

DUT

LMD Light

source

φ

θ

Figure 7a – Directional illumination – Side view Figure 7b – Directional illumination – Top view

Figure 7 – Side-view of the measuring set-up using directional illumination

The light-source as well as the LMD in this set-up can be adjusted to a range of angles of

inclinations, but the LMD shall remain in the plane of light-incidence (i.e φS = φR + 180 °)

Alignment accuracy to within 0,2 ° is required to achieve good reproducibility [15], [17]

This configuration is shown in Figure 7a, with its representation in a polar coordinate system

(Figure 7b) for, in this example, an angle of LMD-inclination, θR = 30 ° and angle of source

inclination, θS = 40 °

NOTE Standard conditions of θS = 0 ° and θR = 30 ° are recommended Alignment accuracy to within ± 0,4 ° is

recommended to assure measurement error within ± 5 % [16]

Figure 8a – Ring illumination – Side view Figure 8b – Ring illumination – Top view

Figure 8 – Side-view of the ring-light illumination measuring set-up

The measuring spot on the DUT as "seen" by the LMD shall be enclosed and centered in the illuminated area on the DUT and it shall be illuminated in a uniform way The width of the ring light shall be specified The source and detector shall be aligned to the defined geometry to within +3 ° [15], [17]

This set-up is used with the source fixed and the LMD can remain adjustable within the limits

of the opening of the illuminating ring of light

NOTE Standard conditions of θR = 0 ° and a subtense of the source of θS ± ∆ = (20 ± 3) ° are recommended Alignment accuracy to within ± 0,7 ° is recommended to assure measurement error within ± 5% [16]

4.3.4 Conical illumination

A light-source centred about the surface normal of the DUT illuminates the DUT from a range

of inclination angles θS (0 ° < θS < θS-max) for all azimuthal angles φS = 0 ° - 360 ° The LMD

is aligned to form an angle θR with respect to the surface normal of the DUT Figure 9 shows

a side-view of the measuring set-up (left) and its representation in a polar coordinate system (Figure 9b) for, in this example, an angle of LMD-inclination, θR = 50 ° and a subtense of the

IEC 962/11

IEC 963/11

source, 2 x θS-max = 120 ° The measurement field on the DUT is defined by the area element that is imaged on the detector of the LMD

LMD

φ

θ

DUT

Figure 9a – Conical illumination – Side view Figure 9b – Conical illumination – Top view

Figure 9 – Side-view of the conical illumination measuring set-up

The distance of the source from the DUT shall be accurate within 5 mm and the direction of the illuminating device shall be aligned within 4 ° The LMD shall be aligned within 0,5 ° Means shall be provided for the LMD to look on the DUT through the illuminating device (e.g slit, aperture) The actual realization shall be specified in detail [15], [17]

NOTE 1 Standard conditions of θR = 0 ° and a subtense of the source, 2 x θS-max = 90 ° are recommended

Alignment accuracy of θS-max within ± 1,5 ° is recommended to assure measurement error within ± 5 % [16]

NOTE 2 When the display has a haze component, caution should be used to ensure proper angle and geometry to assure reproducibility and accuracy of the measurement

4.3.5 Hemispherical illumination

A light-source centred about the surface normal of the DUT illuminates the DUT from a range

of inclination angles 0 ° <= θS <= 90 ° for all azimuthal angles φS = 0 ° - 360 ° The LMD is aligned to form an angle θR < θS with respect to the surface normal of the DUT

Figure 10a shows a side-view of the measuring set-up and its representation in a polar coordinate system (Figure 10b) for, in this example, an angle of LMD-inclination, θR = 40 ° and a subtense of the source, 2 x θS-max = 140 ° The measurement field on the DUT is defined by the area element that is imaged on the detector of the LMD

IEC 965/11

IEC 964/11

source, 2 x θS-max = 120 ° The measurement field on the DUT is defined by the area element

that is imaged on the detector of the LMD

LMD

φ

θ

DUT

Figure 9a – Conical illumination – Side view Figure 9b – Conical illumination – Top view

Figure 9 – Side-view of the conical illumination measuring set-up

The distance of the source from the DUT shall be accurate within 5 mm and the direction of

the illuminating device shall be aligned within 4 ° The LMD shall be aligned within 0,5 °

Means shall be provided for the LMD to look on the DUT through the illuminating device (e.g

slit, aperture) The actual realization shall be specified in detail [15], [17]

NOTE 1 Standard conditions of θR = 0 ° and a subtense of the source, 2 x θS-max = 90 ° are recommended

Alignment accuracy of θS-max within ± 1,5 ° is recommended to assure measurement error within ± 5 % [16]

NOTE 2 When the display has a haze component, caution should be used to ensure proper angle and geometry to

assure reproducibility and accuracy of the measurement

4.3.5 Hemispherical illumination

A light-source centred about the surface normal of the DUT illuminates the DUT from a range

of inclination angles 0 ° <= θS <= 90 ° for all azimuthal angles φS = 0 ° - 360 ° The LMD is

aligned to form an angle θR < θS with respect to the surface normal of the DUT

Figure 10a shows a side-view of the measuring set-up and its representation in a polar

coordinate system (Figure 10b) for, in this example, an angle of LMD-inclination, θR = 40 °

and a subtense of the source, 2 x θS-max = 140 ° The measurement field on the DUT is

defined by the area element that is imaged on the detector of the LMD

Figure 10 a – Hemispherical illumination – Side view Figure 10b – Hemispherical illumination – Top view

Figure 10 – Side-view of the hemispherical illumination measuring set-up

Means shall be provided for the LMD to look on the DUT through the illuminating device (e.g slit, aperture) Alignment accuracy for repeatable measurements shall be better than ± 5 ° [15], [17]

NOTE Standard conditions of θR = 0 ° and a subtense of the source, 2 x θS-max = 180 ° are recommended

Alignment accuracy of θS-max within -6 ° to 0 ° is recommended to assure measurement error within ± 5 % [17]

4.3.6 Other illumination conditions

The standard arrangements for carrying out the measurements as listed above are included

as examples Other combinations may also be used, as long as the arrangement is specified

in detail to assure proper reproducibility (see below)

4.4 Standard specification of measurement conditions 4.4.1 Illumination conditions

The characteristics of illumination can be characterized in the following terms and quantities:

• an integral intensity (e.g luminance) and spectrum or tri-stimulus-values X, Y, Z versus

direction of light incidence and versus position on the sample (lateral variations),

• temporal characteristics (short and long-term variations) of an integral intensity (e.g luminance)

The differential illuminance dE of the measuring spot from the direction (θ, φ) is a function of

the luminance L(θ, φ) of the light source, the differential solid angle dΩ(θ) and the direction of light incidence as seen from the perspective of the measuring spot and described by the polar angles θ, φ as follows:

IEC 966/11

IEC 967/11

– 18 – 61747-6-2  IEC:2011

This is illustrated by the graph in Figure 12, showing the normalized illuminance at the location of the measuring spot as a function of the angle of inclination θ (for a specific azimuth angle φ, Figure 12a) and as a function of the azimuth angle φ (for a specific angle of inclination θ, Figure 12b) for the hemispherical geometry with gloss-trap shown in Figure 11 (θmax = 70 °)

Whenever illumination at the location of the measuring spot on the DUT shall be characterized

by spectral distributions as a function of the direction of light-incidence, irradiance has to be used instead of illuminance

All light sources and illumination devices used for the measurements according to this standard shall provide an illumination that is perceived as "white" by a human observer

Figure 11 – Hemispherical illumination with gloss-trap (GT)

opposite to receiver inclination

Figure 12a – Measured luminance as function of θ Figure 12b – Measured luminance as function ofφ

Figure 12 – Normalized illuminance at the location of the measuring spot

Since the spectrum of illumination cannot be graphically represented as a function of the

direction of light incidence, chromaticity differences such as ∆u', ∆v' (with respect to the

Whenever illumination at the location of the measuring spot on the DUT shall be characterized

by spectral distributions as a function of the direction of light-incidence, irradiance has to be used instead of illuminance

All light sources and illumination devices used for the measurements according to this standard shall provide an illumination that is perceived as "white" by a human observer

Figure 11 – Hemispherical illumination with gloss-trap (GT)

opposite to receiver inclination

Figure 12a – Measured luminance as function of θ Figure 12b – Measured luminance as function ofφ

Figure 12 – Normalized illuminance at the location of the measuring spot

Since the spectrum of illumination cannot be graphically represented as a function of the

direction of light incidence, chromaticity differences such as ∆u', ∆v' (with respect to the

C O R R I G E N D U M 1

Figures 11 and 12

Replace existing Figures 11 and 12 by the following new figures:

Gloss trap Receiver slit

A

A



 B

IEC 040/12

Figure 11– Hemispherical illumination with gloss-trap (GT)

opposite to receiver inclination

Cross section A-A

Figure 12a – Measured luminance as function of  Figure 12b – Measured luminance as function of 

Figure 12 – Normalized illuminance at the location of the measuring spot

5.1.3 Measuring method

Replace existing items a) to d) by the following new items, so as to include the procedure for determining the WWS reflectance:

a) Select one of the standard measuring systems

b) Place the WWS at the position where the DUT will be placed for subsequent

measurement and measure Rw’(





61747-6-2  IEC:2011 – 19 – chromaticity of the light in a reference direction, e.g normal) are chosen instead

(see Figure 13: Lines of equal chromaticity differences ∆u' (Figure 13a) and ∆v' (Figure 13b)

as a function of the direction of light incidence θ, φ with reference to the normal direction illustrated for the hemispherical illumination with gloss-trap shown in Figure 11) The ideal illumination would not exhibit any chromaticity variations with direction of light incidence and thus the chromaticity differences would be zero for all directions

φ

θ S1

R

φ

θ

Figure 13a – Chromaticity difference ∆u' Figure 13b – Chromaticity difference ∆v’

Figure 13 – Lines of equal chromaticity differences ∆u' ∆v'

The temporal variations of the light sources used for generating well-defined illumination conditions shall be measured and reported on a short-time scale (e.g several thousands of samples with ms resolution) and on a long-time scale (several thousand samples with a resolution in the range of seconds) For characterization of temporal fluctuations and variations it is sufficient to measure and evaluate photometric quantities (e.g luminance, illuminance, etc.), spectra are not required When spectral fluctuations occur (e.g in discharge lamps) this is usually noticed by fluctuations of photometric quantities as well

4.4.2 LMD conditions

From the distance of the LMD to the measurement field and the aperture of the LMD (acceptance area) the angular aperture of the LMD has to be evaluated and specified (see Figure A.2)

When measuring matrix displays the LMD should be set to a circular or rectangular field of view that includes more than 500 pixels2 on the display under normal observation (the standard measurement direction) The total acceptance angle of detection by the LMD, θacceptshall be less than 2 ° This can, for example, be obtained by use of a measuring distance between the LMD and display area centre of 50 cm (recommended) and a diameter of the detector pupil of 4 cm For low-resolution matrix displays, the number of pixels in the field of view may be lower than 500 Here, a minimum of 9 pixels is recommended In case of measuring segment displays, the field of view should be set to a single segment, and not include any of its surroundings

Before each measurement, the LMD shall be calibrated by measuring the reflectance of a WWS (Working White Standard), at the same position that will be taken later by the DUT

This is illustrated by the graph in Figure 12, showing the normalized illuminance at the

location of the measuring spot as a function of the angle of inclination θ (for a specific azimuth

angle φ, Figure 12a) and as a function of the azimuth angle φ (for a specific angle of

inclination θ, Figure 12b) for the hemispherical geometry with gloss-trap shown in Figure 11

(θmax = 70 °)

Whenever illumination at the location of the measuring spot on the DUT shall be characterized

by spectral distributions as a function of the direction of light-incidence, irradiance has to be

used instead of illuminance

All light sources and illumination devices used for the measurements according to this

standard shall provide an illumination that is perceived as "white" by a human observer

Figure 11 – Hemispherical illumination with gloss-trap (GT)

opposite to receiver inclination

Figure 12a – Measured luminance as function of θ Figure 12b – Measured luminance as function ofφ

Figure 12 – Normalized illuminance at the location of the measuring spot

Since the spectrum of illumination cannot be graphically represented as a function of the

direction of light incidence, chromaticity differences such as ∆u', ∆v' (with respect to the

IEC 968/11

IEC 969/11 IEC 970/11

BS EN 61747-6-2:2011

This is illustrated by the graph in Figure 12, showing the normalized illuminance at the

location of the measuring spot as a function of the angle of inclination θ (for a specific azimuth

angle φ, Figure 12a) and as a function of the azimuth angle φ (for a specific angle of

inclination θ, Figure 12b) for the hemispherical geometry with gloss-trap shown in Figure 11

(θmax = 70 °)

Whenever illumination at the location of the measuring spot on the DUT shall be characterized

by spectral distributions as a function of the direction of light-incidence, irradiance has to be

used instead of illuminance

All light sources and illumination devices used for the measurements according to this

standard shall provide an illumination that is perceived as "white" by a human observer

Figure 11 – Hemispherical illumination with gloss-trap (GT)

opposite to receiver inclination

Figure 12a – Measured luminance as function of θ Figure 12b – Measured luminance as function ofφ

Figure 12 – Normalized illuminance at the location of the measuring spot

Since the spectrum of illumination cannot be graphically represented as a function of the

direction of light incidence, chromaticity differences such as ∆u', ∆v' (with respect to the

IEC 968/11

IEC 969/11 IEC 970/11

4.4.3 Unwanted effects of receiver inclination

When the measuring set-up comprises an adjustable LMD for measurement and evaluation of variations with viewing-direction, it has to be taken into account that the receiver of the LMD

"sees" different parts of the DUT at different angles of inclination An initially circular measuring spot (when the DUT is viewed or measured from normal) becomes elliptical when the receiver is inclined away from the normal direction, as shown in Figure 14 The short axis

of the ellipse (here: vertical) remains constant with the plane of inclination being the plane perpendicular to the paper surface, intersecting with the paper surface along the long axis of the ellipse (here: horizontal)

Figure 14 – Shape of measuring spot on DUT for two angles of receiver inclination

Two effects have to be considered when the receiver is adjustable The increasing size of the measuring spot with angle of inclination shall not include

• unwanted parts of the DUT (e.g non-active parts of a display with segment-layout), or

• parts illuminated in a different way

Both size and location of the measurement field have to be selected that these conditions are fulfilled and they have to be specified accordingly

4.4.4 Control and suppression of front-surface reflections

Whenever there is a light-source at the specular angle of the LMD, reflections from the surface of the DUT are superimposed to the reflection components that are modulated by the display device These front surface reflections are in the range of some percent of the incident light flux and they can severely reduce the contrast of a reflective display [12], 13] Depending on various factors, such front-surface reflections may be included in the measurement (for reproduction of real application situations) or they may be suppressed and excluded (for approximation of ideal application situations)

front-It has to be specified if front-surface reflections are included in the measurement and if they are not included, it has to be specified in detail how they have been excluded in order to make the measurement reproducible

IEC 973/11

4.4.3 Unwanted effects of receiver inclination

When the measuring set-up comprises an adjustable LMD for measurement and evaluation of

variations with viewing-direction, it has to be taken into account that the receiver of the LMD

"sees" different parts of the DUT at different angles of inclination An initially circular

measuring spot (when the DUT is viewed or measured from normal) becomes elliptical when

the receiver is inclined away from the normal direction, as shown in Figure 14 The short axis

of the ellipse (here: vertical) remains constant with the plane of inclination being the plane

perpendicular to the paper surface, intersecting with the paper surface along the long axis of

the ellipse (here: horizontal)

Figure 14 – Shape of measuring spot on DUT for two angles of receiver inclination

Two effects have to be considered when the receiver is adjustable The increasing size of the

measuring spot with angle of inclination shall not include

• unwanted parts of the DUT (e.g non-active parts of a display with segment-layout), or

• parts illuminated in a different way

Both size and location of the measurement field have to be selected that these conditions are

fulfilled and they have to be specified accordingly

4.4.4 Control and suppression of front-surface reflections

Whenever there is a light-source at the specular angle of the LMD, reflections from the

front-surface of the DUT are superimposed to the reflection components that are modulated by the

display device These front surface reflections are in the range of some percent of the

incident light flux and they can severely reduce the contrast of a reflective display [12], 13]

Depending on various factors, such front-surface reflections may be included in the

measurement (for reproduction of real application situations) or they may be suppressed and

excluded (for approximation of ideal application situations)

It has to be specified if front-surface reflections are included in the measurement and if they

are not included, it has to be specified in detail how they have been excluded in order to make

the measurement reproducible

4.5.1 Diffuse reflectance standard

Diffuse (white) reflectance standard samples can be obtained with diffuse reflectance of 98 %

or more They are also available in different shades of gray Some materials can be carefully sanded (some require water with the sanding) or cleaned to refresh the surface back up to its maximum reflectance should the surface become soiled or contaminated Such reflectance standards can be used for making illuminance from a luminance measurement of the standard

(E = π Lstd / βstd) only for the measurement geometry used to determine its luminance factor

βstd —the geometry used to calibrate the standard If the reflectance (or diffuse reflectance) is associated with the standard – as the number of 98 % or 99 % usually refers to the reflectance – then that value can only be used for a uniform hemispherical illumination If an isolated source at some angle is used, there is no reason to expect that the 99 % value is even close to the proper value of the luminance factor for that geometrical configuration

4.5.2 Specular reflectance standard

Black glass (e.g., BG-1000) or a very high neutral density absorption filter (density of 4 or larger) can be used to measure the luminance of a source provided that the specular reflection properties are properly calibrated Such a reflector acts much like a front surface mirror that has a low specular reflectance of usually between 4 % and 5 % These can be helpful when you can only see the source using a mirror, or when you want to measure the luminance at the same order of magnitude of a reflection measurement rather than measuring the source directly Note that how you clean the surface and the specular angle that is used will affect the value of the specular reflectance, so it must be calibrated for each configuration

to obtain valid results [16]

IEC 974/11

4.6 Standard locations of measurement field

4.6.1 Matrix displays

(5/10)V (3/10)V (1/10)V (1/10)H (3/10)H (5/10)H

P19 P20 P21 P22 P23

P18 P6 P7 P8 P24

P16 P4 P3 P2 P10

P15 P14 P13 P12 P11

P17 P5 P0 P1 P9

Figure 16 – Standard measurement positions at the centres of all rectangles p0-p24 – Height and width of each rectangle is 20 %

of display height and width respectively

Luminance, spectral distribution and/or tristimulus measurements may be taken at several specified positions on the DUT surface To this end the front view of the display is divided into

25 identical imaginary rectangles, according to Figure 16 Unless otherwise specified, measurements are carried out in the centre of each rectangle Care shall be taken that the measuring spots on the display do not overlap Positioning of the measuring spot on the thus

prescribed positions in the x and y direction shall be to within 7 % of H and V respectively (where H and V denote the length of the active display area in the x and y direction

Any deviation from the above-described standard positions shall be added to the detail specification

IEC 975/11

4.6 Standard locations of measurement field

4.6.1 Matrix displays

(5/10)V (3/10)V

(1/10)V (1/10)H

(3/10)H (5/10)H

P19 P20 P21 P22 P23

P18 P6 P7 P8 P24

P16 P4 P3 P2 P10

P15 P14 P13 P12 P11

P17 P5 P0 P1 P9

Figure 16 – Standard measurement positions at the centres of all rectangles p0-p24 – Height and width of each rectangle is 20 %

of display height and width respectively

Luminance, spectral distribution and/or tristimulus measurements may be taken at several

specified positions on the DUT surface To this end the front view of the display is divided into

25 identical imaginary rectangles, according to Figure 16 Unless otherwise specified,

measurements are carried out in the centre of each rectangle Care shall be taken that the

measuring spots on the display do not overlap Positioning of the measuring spot on the thus

prescribed positions in the x and y direction shall be to within 7 % of H and V respectively

(where H and V denote the length of the active display area in the x and y direction

respectively)

While scanning the position of the measuring spot over the surface of the DUT, the polar

angles shall stay fixed

Any deviation from the above-described standard positions shall be added to the detail

specification

4.6.2 Segment displays

Standard measurement positions are the same as those prescribed for matrix displays above

However, for segment displays, all measurements shall be performed at the centre of a

segment and the chosen segment should be as close as possible to the centre of the

designated rectangle Thus, when measurements on position pi (i = 0 to 24) are requested,

the geometrical centre of the segment closest to the centre of box pi should be used for

positioning of the detector

Any deviation from the above-described standard positions shall be added to the detail

of the viewing direction is nercessary Also, the distance between the light measuring device and the measuring spot on the DUT has to remain constant for all viewing-directions

All light sources used for illumination of the DUT during the measurement shall be constant in illuminance and spectrum at least over the time-period of measurements that are related to each other in the evaluation (e.g bright and dark state of a display for contrast evaluation) The luminance or illuminance of the arrangement used for illumination of the DUT shall be constant within ± 1 %, and shall not exhibit short-term fluctuations (e.g ripple, PWM-modulations, etc.) This should be realized by an equilibration period of 5 min to 10 min Constant and correct temperature of the DUT shall be verified

The module being tested shall be physically prepared for testing It should be thermostatically controlled for stable operation of liquid crystal display devices during a specified period being less than 1 h If the control period is less than 1 h, stable temperature shall be verified Testing shall be conducted under nominal conditions of input voltage, current, etc Any deviation from the standard device operation conditions shall be added to the detail specification

4.7.2 Standard ambient conditions 4.7.2.1 Standard measuring environmental conditions

Measurements shall be carried out, after sufficient warm-up time for illumination sources and devices under test (see below), under the standard environmental conditions, at a temperature of 25 ºC ± 3 ºC, at a relative humidity of 25 % to 85 %, and at an atmospheric pressure of 86 kPa to 106 kPa When different environmental conditions are used, they shall

be noted in the report

Warm-up time is defined as the time required to obtain a luminance stability of ± 5 % variation per hour of operation

4.7.2.2 Standard illumination conditions

Reflective LCD modules do not have built-in light sources The light source, the relative position between the light source and the device under test (DUT), and the relative position between the DUT and the measurement equipment are restricted Four different types may be used as the standard measuring illumination systems The optical systems are schematically shown in Figure 7, Figure 8, Figure 9 and Figure 10

Each system is positioned in a dark measuring room The illuminance of the DUT not originating from the light source is less than 1 lx, and the illuminance by the light source is more than 300 lx When measuring matrix displays the measurement field should be set to a circular or rectangular field of view that includes more than 500 pixels on the display under normal incidence (the standard measurement direction) If the field of view is less than

500 pixels, its condition shall be specified in the detail specification The measuring result of LCD modules is affected by the illumination and geometrical conditions This standard poses restrictions on the measurement conditions The conditions following from these restrictions shall be specified in the detail specification

4.8 Standard measuring process

The standard measuring process comprises the following basic steps:

– 24 – 61747-6-2  IEC:2011 a) Preparation of the measurement equipment and set-up, of the device-under-test and of

the ambient conditions to assure the specified standard values and stabilities Whenever

the actual conditions differ from the standard conditions, this shall be noted in the report

and the actually used values shall be specified in the report

b) While assuring the usual care required in an optical metrology laboratory, the sample

reflectance shall be measured in terms of luminance, spectral radiance distribution or

tri-stimulus values under the specified illumination conditions and with the specified electrical

driving conditions (voltages, test-patterns, etc.)

c) While assuring the usual care required in an optical metrology laboratory, the reflectance

of the applicable reference standard(s) shall be measured in terms of luminance, spectral

radiance distribution or tri-stimulus values under the specified illumination conditions

which shall be identical to those used for the measurements of the DUT

d) The data obtained from measurement of the DUT and the data obtained from the

measurement of the reference standard shall be related to each other in a suitable way in

order to obtain the target data (e.g reflected luminance, chromaticity of reflected light,

etc.) The way in which calculations are made shall be according to established rules (e.g

as given in [18]) and it shall be specified in the measurement report

e) If the arrangements of light-source(s), DUT and light measurement device used for the

measurements are different from the ones described in 4.3, the really used arrangement

shall be specified in detail in the measurement report A detailed drawing and photos of

the arrangement are useful to complete such a specification

5 Standard measurements and evaluations

An LMD, a driving power supply and a driving signal generator for liquid crystal display

devices and a temperature control device for the DUT are used for these measurements For

lateral uniformity measurements, a dual axis positioning device may also be required

5.1.3 Measuring method

The measurements are performed in the dark room under standard measuring conditions and

design viewing direction

a) Select one of the standard measuring systems and set the DUT

b) Supply the signals to the device so that the contrast ratio is maximised to the full WHITE

conditions Then measure the DUT at position p0 (the centre of the active area of the

display) to obtain tristimulus values; Xon, Yon, Zon

c) Supply the signals to the device to the full BLACK conditions Then measure the

reflectance R0 at position p0 to obtain tristimulus values; Xoff, Yoff, Zoff

d) Determine reflectance of the full WHITE; Ron as Yon, and reflectance of the full BLACK;

Roff as Yoff

NOTE In some cases, the DUT may display a black image in the “on” state, and a white image in the “off” state In

this case, the terminology Ron, Xon, Yon, Zon will apply to the BLACK state, and Roff, Xoff, Yoff, Zoff will apply to

the WHITE state

BS EN 61747-6-2:2011

a) Preparation of the measurement equipment and set-up, of the device-under-test and of

the ambient conditions to assure the specified standard values and stabilities Whenever

the actual conditions differ from the standard conditions, this shall be noted in the report

and the actually used values shall be specified in the report

b) While assuring the usual care required in an optical metrology laboratory, the sample

reflectance shall be measured in terms of luminance, spectral radiance distribution or

tri-stimulus values under the specified illumination conditions and with the specified electrical

driving conditions (voltages, test-patterns, etc.)

c) While assuring the usual care required in an optical metrology laboratory, the reflectance

of the applicable reference standard(s) shall be measured in terms of luminance, spectral

radiance distribution or tri-stimulus values under the specified illumination conditions

which shall be identical to those used for the measurements of the DUT

d) The data obtained from measurement of the DUT and the data obtained from the

measurement of the reference standard shall be related to each other in a suitable way in

order to obtain the target data (e.g reflected luminance, chromaticity of reflected light,

etc.) The way in which calculations are made shall be according to established rules (e.g

as given in [18]) and it shall be specified in the measurement report

e) If the arrangements of light-source(s), DUT and light measurement device used for the

measurements are different from the ones described in 4.3, the really used arrangement

shall be specified in detail in the measurement report A detailed drawing and photos of

the arrangement are useful to complete such a specification

5 Standard measurements and evaluations

An LMD, a driving power supply and a driving signal generator for liquid crystal display

devices and a temperature control device for the DUT are used for these measurements For

lateral uniformity measurements, a dual axis positioning device may also be required

5.1.3 Measuring method

The measurements are performed in the dark room under standard measuring conditions and

design viewing direction

a) Select one of the standard measuring systems and set the DUT

b) Supply the signals to the device so that the contrast ratio is maximised to the full WHITE

conditions Then measure the DUT at position p0 (the centre of the active area of the

display) to obtain tristimulus values; Xon, Yon, Zon

c) Supply the signals to the device to the full BLACK conditions Then measure the

reflectance R0 at position p0 to obtain tristimulus values; Xoff, Yoff, Zoff

d) Determine reflectance of the full WHITE; Ron as Yon, and reflectance of the full BLACK;

Roff as Yoff

NOTE In some cases, the DUT may display a black image in the “on” state, and a white image in the “off” state In

this case, the terminology Ron, Xon, Yon, Zon will apply to the BLACK state, and Roff, Xoff, Yoff, Zoff will apply to

the WHITE state

BS EN 61747-6-2:2011

C O R R I G E N D U M 1

Figures 11 and 12

Replace existing Figures 11 and 12 by the following new figures:

Gloss trap Receiver slit

A

A



 B

IEC 040/12

Figure 11– Hemispherical illumination with gloss-trap (GT)

opposite to receiver inclination

Cross section A-A

Figure 12a – Measured luminance as function of  Figure 12b – Measured luminance as function of 

Figure 12 – Normalized illuminance at the location of the measuring spot

5.1.3 Measuring method

Replace existing items a) to d) by the following new items, so as to include the procedure for

determining the WWS reflectance:

a) Select one of the standard measuring systems

b) Place the WWS at the position where the DUT will be placed for subsequent

measurement and measure Rw’(

c) Place the DUT at the correct measuring position

d) Supply the signals to the device so that the contrast ratio is maximised to the full

WHITE conditions Then measure the DUT at position p0 (the centre of the active area

of the display) to obtain tristimulus values; Xon, Yon, Zon.

e) Supply the signals to the device to the full BLACK conditions Then measure the

reflectance R0 at position p0 to obtain tristimulus values; Xoff, Yoff, Zoff

f) Determine reflectance of the full WHITE; Ron as Yon, and reflectance of the full

BLACK; Roff as Yoff.

5.4.3 Measuring method

Replace existing items a) to d) by the following new items, so as to include the procedure for

determining the WWS reflectance:

a) Place the WWS at the position where the DUT will be placed for subsequent

measurement and measure Xwws, Ywws, Zwws Use the measurement data for

calibration of the LMD, or for subsequent correction of the measured data

b) Position the DUT at position p0 (the centre of the active area of the display) and

supply the maximum value of the colour input-signals of the primaries R (red), G

(green) and B (blue) simultaneously to the device Next, maximise the contrast ratio at

this value of the input primaries Then measure the DUT to obtain tristimulus values;

Xon, Yon, Zon.

c) Place the DUT and supply the signals to the device to the full BLACK conditions Then

measure the position p0 to obtain tristimulus values; Xoff, Yoff, Zoff.

d) Supply the signals of any intermediate (grey) states, if required Then for n

intermediate states measure the position p0 to obtain tristimulus values Xg1 Xgn; Yg1

Ygn; Zg1 Zgn

e) Finally separately supply the maximum R-data input-signal to the device, with data

input of the complimentary primaries set to minimum or zero, and measure the red

colour tristimulus values; XR, YR, ZR.

f) In the same way measure the green and blue colour tristimulus values; XG, YG, ZG,

and XB, YB, ZB respectively

5.5.4 Evaluation and representation

Replace Equation (22) by the following new equation:

5.6.4 Evaluation and representation

Replace Equation (23) by the following new equation:

Rλ(ED-i) = Rλ(std) x Lλ-i (DUT) / Lλ(std) (23)

Replace Equation (24) by the following new equation:

R X/Y/Z (ED-i) = R X/Y/Z (std) x L X/Y/Z -i (DUT) / L X/Y/Z(std) (24)





– 24 – 61747-6-2  IEC:2011 a) Preparation of the measurement equipment and set-up, of the device-under-test and of

the ambient conditions to assure the specified standard values and stabilities Whenever

the actual conditions differ from the standard conditions, this shall be noted in the report

and the actually used values shall be specified in the report

b) While assuring the usual care required in an optical metrology laboratory, the sample

reflectance shall be measured in terms of luminance, spectral radiance distribution or

tri-stimulus values under the specified illumination conditions and with the specified electrical

driving conditions (voltages, test-patterns, etc.)

c) While assuring the usual care required in an optical metrology laboratory, the reflectance

of the applicable reference standard(s) shall be measured in terms of luminance, spectral

radiance distribution or tri-stimulus values under the specified illumination conditions

which shall be identical to those used for the measurements of the DUT

d) The data obtained from measurement of the DUT and the data obtained from the

measurement of the reference standard shall be related to each other in a suitable way in

order to obtain the target data (e.g reflected luminance, chromaticity of reflected light,

etc.) The way in which calculations are made shall be according to established rules (e.g

as given in [18]) and it shall be specified in the measurement report

e) If the arrangements of light-source(s), DUT and light measurement device used for the

measurements are different from the ones described in 4.3, the really used arrangement

shall be specified in detail in the measurement report A detailed drawing and photos of

the arrangement are useful to complete such a specification

5 Standard measurements and evaluations

An LMD, a driving power supply and a driving signal generator for liquid crystal display

devices and a temperature control device for the DUT are used for these measurements For

lateral uniformity measurements, a dual axis positioning device may also be required

5.1.3 Measuring method

The measurements are performed in the dark room under standard measuring conditions and

design viewing direction

a) Select one of the standard measuring systems and set the DUT

b) Supply the signals to the device so that the contrast ratio is maximised to the full WHITE

conditions Then measure the DUT at position p0 (the centre of the active area of the

display) to obtain tristimulus values; Xon, Yon, Zon

c) Supply the signals to the device to the full BLACK conditions Then measure the

reflectance R0 at position p0 to obtain tristimulus values; Xoff, Yoff, Zoff

d) Determine reflectance of the full WHITE; Ron as Yon, and reflectance of the full BLACK;

Roff as Yoff

NOTE In some cases, the DUT may display a black image in the “on” state, and a white image in the “off” state In

this case, the terminology Ron, Xon, Yon, Zon will apply to the BLACK state, and Roff, Xoff, Yoff, Zoff will apply to

the WHITE state

The spectral reflectance factor; R(λ) of the DUT is determined by comparing the DUT to the

calibrated WWS The example gives the measurement procedure for single beam instruments, but dual beam instruments can also be used The measuring process is as follows

a) Measure WWS, and read a value of Rw’(λ)

b) Replace the WWS by the DUT and read a value of R’(λ)

c) Determine the spectral reflectance factor; R(λ) of the DUT according to the next formula:

w R

R Rw

where

R(λ)is the spectral reflectance factor of the DUT;

R’(λ) is a value of each wavelength of the DUT;

Rw’(λ) is a value of each wavelength of WWS;

Rw(λ) is the spectral reflectance factor of WWS calibrated by the same geometry

as the spectrophotometer used for measuring

d) Tristimulus values; X, Y, Z are calculated in principle as follows:

λ λ λ

= ∑780 ( ) ( ) ( )

380

R x S K

λ λ λ

= ∑780 ( ) ( ) ( )

380

R y S K

λ λ λ

= ∑780 ( ) ( ) ( )

380

R z S K

λ λ

y S

where

S(λ) is the spectral intensity distribution of the standard illuminant;

x(λ), y(λ), z(λ) is the colour matching function for CIE 1931 standard observer;

R(λ) is the spectral reflectance factor of the DUT;

∆(λ) is the wavelength interval for tristimulus values calculation

a) Preparation of the measurement equipment and set-up, of the device-under-test and of

the ambient conditions to assure the specified standard values and stabilities Whenever

the actual conditions differ from the standard conditions, this shall be noted in the report

and the actually used values shall be specified in the report

b) While assuring the usual care required in an optical metrology laboratory, the sample

reflectance shall be measured in terms of luminance, spectral radiance distribution or

tri-stimulus values under the specified illumination conditions and with the specified electrical

driving conditions (voltages, test-patterns, etc.)

c) While assuring the usual care required in an optical metrology laboratory, the reflectance

of the applicable reference standard(s) shall be measured in terms of luminance, spectral

radiance distribution or tri-stimulus values under the specified illumination conditions

which shall be identical to those used for the measurements of the DUT

d) The data obtained from measurement of the DUT and the data obtained from the

measurement of the reference standard shall be related to each other in a suitable way in

order to obtain the target data (e.g reflected luminance, chromaticity of reflected light,

etc.) The way in which calculations are made shall be according to established rules (e.g

as given in [18]) and it shall be specified in the measurement report

e) If the arrangements of light-source(s), DUT and light measurement device used for the

measurements are different from the ones described in 4.3, the really used arrangement

shall be specified in detail in the measurement report A detailed drawing and photos of

the arrangement are useful to complete such a specification

5 Standard measurements and evaluations

An LMD, a driving power supply and a driving signal generator for liquid crystal display

devices and a temperature control device for the DUT are used for these measurements For

lateral uniformity measurements, a dual axis positioning device may also be required

5.1.3 Measuring method

The measurements are performed in the dark room under standard measuring conditions and

design viewing direction

a) Select one of the standard measuring systems and set the DUT

b) Supply the signals to the device so that the contrast ratio is maximised to the full WHITE

conditions Then measure the DUT at position p0 (the centre of the active area of the

display) to obtain tristimulus values; Xon, Yon, Zon

c) Supply the signals to the device to the full BLACK conditions Then measure the

reflectance R0 at position p0 to obtain tristimulus values; Xoff, Yoff, Zoff

d) Determine reflectance of the full WHITE; Ron as Yon, and reflectance of the full BLACK;

Roff as Yoff

NOTE In some cases, the DUT may display a black image in the “on” state, and a white image in the “off” state In

this case, the terminology Ron, Xon, Yon, Zon will apply to the BLACK state, and Roff, Xoff, Yoff, Zoff will apply to

the WHITE state